The digital closed-loop quartz flex accelerometer system is mainly composed of a quartz flex accelerometer header and a digital detection circuit. Its limit precision depends on the sensitivity of the differential capacitance detection circuit. In order to meet the demand for differential capacitance detection in front end of digital closed-loop quartz flex accelerometer

a differential capacitance detection method based on capacitance bridge is presented. Using digital circuit to generate high frequency square wave for single carrier modulation. At the same time

the AC capacitor bridge structure is used to process the carrier signal. The following differential amplifier circuit is designed and the carrier signal is further processed. Finally

the change of weak differential capacitance is detected. The experimental verification shows that the minimum resolution of capacitance detection by the detection circuit is about 1. 8 f F at last

corresponding to acceleration change of 1 μgn.